Gimballed Rocket Engines

[ZeroTheAstronaut]

In a monumentally stupid question, I ask, just HOW do Gimballed Rocket Engines work?

I understand that they use systems to move the nozzle so that the thrust is off center of mass, resulting in torque, turning, etc.

But I have not figured out and am curious as to just how this is done. Is the entire combustion chamber and nozzle shifted, or is the nozzle only moved?

If the nozzle is moving and the combustion chamber is staying still, how does that work? Is the throat between the chamber and the nozzle flexible? Is the nozzle physically separate and just held in place? If that's the case, how are hot exhaust gases not seeping between the connection?

If the combustion chamber moves along with the nozzle, then are most combustion chambers spherical, to facillitate a socket/ball joint?

Hopefully someone knows and can explain. (My google fu has failed me)

Thanks.

[SargeRho]

Some shift the entire engine, some shift the nozzle, others the combustion chamber, nozzle, and have the piping on extra hinges, and others don't move the engine at all, but have paddles in or just after the nozzle - such as the V2.

[Tex_NL]

Your Google-Fu hasn't just failed you. It has completely left you.

Try googling for images :https://www.google.nl/search?q=Gimballed+Rocket+Engine&tbm=isch&tbo=u&source=univ&sa=X&ei=EZ5-UvKwOsic0QWdlIGQBA&ved=0CD8QsAQ&biw=1204&bih=932

[SFJackBauer]

This blog entry from the very own people at NASA that are rebuilding the RS-25 and J-2X engines details the gimballing system:

http://blogs.nasa.gov/J2X/2012/03/05/post_1330983507422/

I recommend reading the other entries of this blog, if you have time.

[K^2]

High power rockets gimball the entire engine. You already have to cool the nozzle with the fuel. Any bends would simply burn through. There is no good way to gimball just the nozzle.

Now, with pumps, you have options. Most of the engines I've seen have the pumps attached to the combustion chamber/nozzle assembly rigidly, but you can, at least in theory, have them on rocket proper.

[ZeroTheAstronaut]

This blog entry from the very own people at NASA that are rebuilding the RS-25 and J-2X engines details the gimballing system:

http://blogs.nasa.gov/J2X/2012/03/05/post_1330983507422/

I recommend reading the other entries of this blog, if you have time.

This answered it exactly. Thank you.

Your Google-Fu hasn't just failed you. It has completely left you.

Try googling for images :https://www.google.nl/search?q=Gimba...w=1204&bih=932

Perhaps I should rephrase that: My understanding of these pictures means nothing without an explanation, and explanations were unforthcoming with my fail of Google.

Thank you all.